See the Getting There section on the Main Page for the hike up and traverse along Sourdough Ridge.
Descend from the NW end of Sourdough ridge into the 4,920+ pass between Sourdough and Elephant Butte. The last 200 feet are steep; veer S and traverse back to avoid the worst of it. As you climb W toward Elephant you have some flexibilty in the route at first. We zigzagged up snowfields and rockbands, avoiding the steepest rock. The map shows a permanent snowfield just above 6000 feet. From the bottom of it, turn left and traverse to the SE ridge. Follow its crest to avoid the steep upper faces and take it to the summit.
We took an alternative route for the descent, working farther S on the snowfields until we reached the little unnamed lake at 5135 feet, dropping down to it from the S. Descend diagonally NE to below 5000 feet, then contour to the pass and hump up onto Sourdough for the return.
Boots and iceaxes. If you're trying to pull this off as a day trip, pack very lightly and don't dawdle.